You use fundamentally to indicate that something affects or relates to the deep, basic nature of something. He disagreed fundamentally with the President's judgment Environmentalists say the treaty is fundamentally flawed. = profoundly. in every way that is important or basic
Primarily; originally; essentially; radically; at the foundation; in origin or constituents
at bottom or by one's (or its) very nature; "He is basically dishonest"; "the argument was essentially a technical one"; "for all his bluster he is in essence a shy person"
emphasis You use fundamentally for emphasis when you are stating an opinion, or when you are making an important or general statement about something. Fundamentally, women like him for his sensitivity and charming vulnerability He can be very charming, but he is fundamentally a bully = basically